Base Station Filter With Direct Resonant Cavity Coupling
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Solution Overview
Problem
Conventional filters for base stations face challenges in achieving high outband suppression due to complex and unreliable indirect coupling methods, which are difficult to implement, especially in compact designs with multiple channels, leading to poor reliability and consistency.
Innovation Solution
A filter design featuring a filter body with resonant cavities and ports that are inductively or capacitively coupled, where additional resonant cavities are connected in series to the input or output ports, allowing for a flexible layout and simpler coupling structures, enhancing reliability and consistency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If indirect coupling methods are used to form finite transmission zeroes, then outband suppression requirement is met, but structure becomes complex and reliability deteriorates
Solution Approach 1:
The patent extracts the complex indirect coupling structure and replaces it with direct coupling between resonant cavities. By removing the intermediate coupling components (metal plates, additional resonant cavities), the design achieves outband suppression through direct inductive or capacitive coupling between adjacent resonant cavities, significantly simplifying the overall structure while maintaining reliability.
Solution Approach 2:
Instead of using indirect coupling through additional resonant cavities and metal plates, the patent inverts the approach by implementing direct coupling between the main resonant cavities. The coupling is achieved through shared walls or direct electromagnetic coupling between adjacent cavities, reversing the conventional indirect coupling methodology.
2Object-affected harmful factors
If additional resonant cavities are coupled to ports to form finite transmission zeroes, then suppression degree is improved, but structure becomes complex and reliability is poor
Solution Approach 1:
The patent merges the function of additional resonant cavities into the main resonant cavity structure. By integrating the coupling function directly into the existing resonant cavities through shared walls or adjacent positioning, the design eliminates the need for separate additional cavities and their associated coupling structures, thereby improving reliability and coupling consistency.
Solution Approach 2:
The resonant cavities in the patent serve multiple functions: they provide the primary resonant function for signal filtering and simultaneously provide the coupling function for forming finite transmission zeroes. This multi-functionality is achieved through the cavity walls that serve both as resonant boundaries and as coupling elements to adjacent cavities.
3Object-affected harmful factors
If cross coupling between non-neighboring resonant cavities is used, then finite transmission zero is generated, but layout requirement becomes very strict
Solution Approach 1:
The patent segments the filter into adjacent resonant cavities that are physically next to each other, rather than using non-neighboring cavities. This segmentation allows the coupling to be implemented between immediately adjacent cavities through shared walls or direct electromagnetic coupling, eliminating the need for complex long-distance routing and strict layout requirements.
Solution Approach 2:
The shared wall or coupling structure between adjacent resonant cavities acts as an intermediary that enables coupling. This intermediary provides a controlled and consistent coupling path between neighboring cavities, achieving the desired finite transmission zero without requiring precise positioning of non-neighboring cavities.
4Object-affected harmful factors
If multiple additional resonant cavities are coupled to ports, then multiple finite transmission zeroes are formed, but manufacturing complexity increases
Solution Approach 1:
The patent merges multiple coupling functions into the main resonant cavity structure. By using the cavity walls and adjacent cavity arrangements to provide multiple coupling paths, the design achieves multiple finite transmission zeroes without requiring separate additional resonant cavities for each zero, thereby simplifying manufacturing and enabling batch production.
Solution Approach 2:
The patent achieves multiple finite transmission zeroes by adjusting parameters such as coupling coefficients between adjacent cavities, resonant frequencies of individual cavities, and coupling wall dimensions. These parameter adjustments allow control over the location and number of transmission zeroes without changing the fundamental direct coupling architecture, making the design manufacturable.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design improves outband suppression characteristics by forming multiple finite transmission zeroes with a simpler and more reliable coupling structure, suitable for high-channel base station filters, facilitating batch production and meeting stringent suppression requirements.
Implementation Method 1
the input port is inductively coupled to one of the resonant cavities, the output port is inductively coupled to another one of the resonant cavities
Implementation Method 2
neighboring resonant cavities are inductively coupled
Implementation Method 3
a first additional resonant cavity in signal coupling to the input port or the output port, and a second additional resonant cavity in signal coupling to the first additional resonant cavity
Data Source
AI summary
The filter is provided, which includes a filter body and resonant cavities disposed on the filter body, and further includes an input port and an output port that are disposed on the filter body. At least one of the input port or the output port is connected to a set of additional resonant cavities, and each set of additional resonant cavities includes: a first additional resonant cavity in signal coupling to the input port or the output port, and a second additional resonant cavity in signal coupling to the first additional resonant cavity. In the filter, the two additional resonant cavities and another resonant cavity connected to the input port or the output port are in a form of a straight line, thereby implementing a flexible layout of cavities of the filter. In addition, a coupling structure is simple, costs are low, reliability and batch consistency is good.